1985 OMC 65, 100 and 155 HP Models Commercial Service Manual, PN 507450-D, Page 387Get this manual
Tilting or Shallow Water Drive While running in the shallow water drive mode, or while the motor is tilted, the following valves and seals are pressurized and must hold: 1The shock absorber valves 2The tilt piston seals
in the tilt cylinder piston
3 The manual release valve
4 The trim pistons seals (Trim pistons are fully extended and the tilttrim separation valve is open 5678The trim check valve The tilt check valve
The trim up relief valve
The impact letdown valve
9At approximately 10,300 kPa (1500 psi) the trim up relief valve will open allowing the oil to return to the reservoir and the filter valve Q) will open replacing oil to the top of the tilt cylinderThis occurs at approximately 1500 rpmThe tilt cylinder will retract, lowering the motor to the fully extended trim rodsRetraction of the trim pistons, under thrust, is prevented by the tilttrim separation valve and the trim check valve The expansion relief valve will remain closed